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https://github.com/c64scene-ar/llvm-6502.git
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529919ff31
Summary: Now that the DataLayout is a mandatory part of the module, let's start cleaning the codebase. This patch is a first attempt at doing that. This patch is not exactly NFC as for instance some places were passing a nullptr instead of the DataLayout, possibly just because there was a default value on the DataLayout argument to many functions in the API. Even though it is not purely NFC, there is no change in the validation. I turned as many pointer to DataLayout to references, this helped figuring out all the places where a nullptr could come up. I had initially a local version of this patch broken into over 30 independant, commits but some later commit were cleaning the API and touching part of the code modified in the previous commits, so it seemed cleaner without the intermediate state. Test Plan: Reviewers: echristo Subscribers: llvm-commits From: Mehdi Amini <mehdi.amini@apple.com> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231740 91177308-0d34-0410-b5e6-96231b3b80d8
118 lines
4.7 KiB
C++
118 lines
4.7 KiB
C++
//===------ SimplifyInstructions.cpp - Remove redundant instructions ------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This is a utility pass used for testing the InstructionSimplify analysis.
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// The analysis is applied to every instruction, and if it simplifies then the
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// instruction is replaced by the simplification. If you are looking for a pass
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// that performs serious instruction folding, use the instcombine pass instead.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Type.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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#define DEBUG_TYPE "instsimplify"
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STATISTIC(NumSimplified, "Number of redundant instructions removed");
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namespace {
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struct InstSimplifier : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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InstSimplifier() : FunctionPass(ID) {
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initializeInstSimplifierPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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AU.addRequired<AssumptionCacheTracker>();
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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}
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/// runOnFunction - Remove instructions that simplify.
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bool runOnFunction(Function &F) override {
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const DominatorTreeWrapperPass *DTWP =
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getAnalysisIfAvailable<DominatorTreeWrapperPass>();
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const DominatorTree *DT = DTWP ? &DTWP->getDomTree() : nullptr;
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const DataLayout &DL = F.getParent()->getDataLayout();
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const TargetLibraryInfo *TLI =
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&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
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AssumptionCache *AC =
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&getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
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SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
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bool Changed = false;
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do {
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for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
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// Here be subtlety: the iterator must be incremented before the loop
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// body (not sure why), so a range-for loop won't work here.
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for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
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Instruction *I = BI++;
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// The first time through the loop ToSimplify is empty and we try to
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// simplify all instructions. On later iterations ToSimplify is not
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// empty and we only bother simplifying instructions that are in it.
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if (!ToSimplify->empty() && !ToSimplify->count(I))
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continue;
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// Don't waste time simplifying unused instructions.
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if (!I->use_empty())
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if (Value *V = SimplifyInstruction(I, DL, TLI, DT, AC)) {
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// Mark all uses for resimplification next time round the loop.
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for (User *U : I->users())
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Next->insert(cast<Instruction>(U));
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I->replaceAllUsesWith(V);
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++NumSimplified;
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Changed = true;
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}
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bool res = RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
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if (res) {
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// RecursivelyDeleteTriviallyDeadInstruction can remove
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// more than one instruction, so simply incrementing the
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// iterator does not work. When instructions get deleted
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// re-iterate instead.
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BI = BB->begin(); BE = BB->end();
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Changed |= res;
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}
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}
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// Place the list of instructions to simplify on the next loop iteration
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// into ToSimplify.
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std::swap(ToSimplify, Next);
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Next->clear();
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} while (!ToSimplify->empty());
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return Changed;
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}
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};
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}
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char InstSimplifier::ID = 0;
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INITIALIZE_PASS_BEGIN(InstSimplifier, "instsimplify",
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"Remove redundant instructions", false, false)
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INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_END(InstSimplifier, "instsimplify",
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"Remove redundant instructions", false, false)
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char &llvm::InstructionSimplifierID = InstSimplifier::ID;
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// Public interface to the simplify instructions pass.
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FunctionPass *llvm::createInstructionSimplifierPass() {
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return new InstSimplifier();
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}
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